MantisBT is an open source issue tracker.
Ranked in these QuestionsQuestion Ranking
Pro Open source
MantisBT is a free and open source bug tracker.
Really light and simple. Good for simple management.
Con Little integration
Supports little integration with code repositories, and CI servers
Con Too simple
Not powerful enough for complex management.
Con No documentation can be found in the installation files
The files that are included with the installer or the files that come out of the box after a fresh installation don't include any documentation.